Yahoo! Movies rides along with stars Jake Gyllenhaal and Michael Pena as they discuss playing partners and being true to the men in blue of South Central Los Angeles in David Ayer's bullet bromance "End of Watch." In a lighter moment, Gyllenhaal joked: "You mix a little 'Serpico' and a little 'Police Academy' and you get 'End of Watch.'"

Thelma Adams: What was the scariest thing about making "End of Watch"?

Jake Gyllenhaal: Honestly, the scariest part of this movie was making sure that we connected as partners in a real way. We emulated the partners that we spent time with on the streets in South Central L.A. in an authentic way. You see actors in movies playing police officers often performing their idea of what a police officer is. And, I think, for us it was about creating something that was like a real ride-along with two police officers, as close as actors can become to being police officers.

Michael Pena: The first meeting I had with [writer-director] David Ayer, he said, 'You guys have to act like brothers, and you guys have to spend a lot of time together to become brothers, and even then you have to spend more time, and then you're going to shoot." Sometimes it felt like I was really talking to [Jake] and not just a character, which I think adds to the reality of it. We wanted it to look like improvisation, like it was the first time we were saying it. And we had to rehearse for five months in order to get that feeling.

JG: Everything was recorded all the time. We shot this movie for $7 million in 22 days. It was the shortest I've ever done in my entire career. I made a movie called "Donnie Darko" that we shot in 28 days. So that was the shortest one I had done until now. It took a lot for us to prepare. We spent five months on the street, two or three times a week on ride-alongs with police officers, sheriffs, LAPD.

TA: Toss me a detail.

JG: My very first ride-along was not with Michael. I was in Inglewood. There was a shooting, and we got there second car on the scene. There was someone murdered. That was my first experience of a ride-along!

MP: Together, we were with the LAPD and it was Code 3, literally sirens.

TA: What does Code 3 mean?

JG: Code 3 is the highest level, meaning usually there's a murder, or domestic violence …

MP: All vehicles go to the location. And we went, and there was this guy shot in the mouth, and, like, you could see the bullet hole in his arm slowly dripping because the bullet was keeping it from bleeding too much. We saw a lot of that stuff. It gives you a reality check. It bursts your bubble that you can sometimes be in living in Hollywood or whatnot. This is the movie, this is the tone that we really want to set -- like people are on a ride-along with us and they experience the movie with us.

JG: What I've heard from people who've seen the movie is that it feels like your heart is beating at the same rate as those two police officers' are. If we're out of breath from chasing a suspect, it's almost as if the audience is the same way. That's the thing that separates it from the genre of cop movies. The other thing is the relationship between these two guys. Again, you see a police officer on the street; they're in a bat suit. They're part of a community that we've all had history with one way or another, whether it's a traffic ticket or being arrested for whatever.

MP: That's dangerous, actually. My favorite is this [he motions someone putting on their seatbelt while driving], trying to get the belt on.

JG: All the actions that people do, because Mike and I could really watch from the back of a cop car and see the behavior when a police car went by. Those people are actually the safe ones. It's the ones that have no response and are almost defiant that are the ones that the police respond to. It's an indecipherable quality that police know. That's what we were trying to pick up, too, sort of understanding the criminal mind and criminal behavior that police know so well that is indecipherable to a civilian.

MP: The first one I learned was the shifty eyes, when they try to clock you and see if you're looking at them. Or if somebody is really still, and there's a little bit of movement here [moves his shoulder], there's something going on. Usually if they're pretty still it's like they know they've done something.

JG: There are even different levels of that, because I think that most people are intimidated by police officers, and intimidation always brings out certain insecurities that might not have anything to do with criminal activity.

MP: We were on one ride-along, and these policemen told us to stay back. We were, like, 'What's going on?' There was a lot of nonverbal communication going on between the officers. Me and Jake clocked it. And we were, like, whoa, this seems a little different. And they put all the guys in the backseat of the police car and they found guns in their car.

JG: Sometimes they'd be, like, 'Tell us who you think we should pull over,' and they would laugh at us over who we thought, and then the cars they would pull over, eventually there would be people I would never suspect. And they would all of a sudden pull out meth from a car you would never assume …

MP: Crazy …

JG: … and it actually is not even racial at a certain point. I'd be surprised at who the police would pull over. It's behavioral.

TA: And how did the police react to you two? Was it fun for them?

JG: It was an added burden on them. You got to look after us and the crime. It's double the fun. At first, I think they thought, as they do with many actors, are these guys for real and do they want to learn what it's really like or do they just want to skirt the surface?

MP: And we kept going. I think we got their respect, and they were able to show us the real deal, and we were able to go to some good calls. And we did gain their trust a little bit by keeping our composure and not messing up a potential scene, not stepping on the evidence.

JG: We alternated between four or five different partners, but after a couple of months they knew that they could trust us. And we knew that we could trust them, and we were really there with them, and hopefully we became less of a burden. I think I speak for both of us when I say that the scariest part of making "End of Watch" was behaving in an authentic way that didn't feel like a performance.

*This interview took place at the Toronto International Film Festival.